1. Field of the Invention
The present invention relates to a freewheel device for a transmission, particularly for a crank CVT of a motor vehicle.
2. Description of the Related Art
DE 102 43 535 A1 discloses a continuously variable transmission that includes an input shaft and an output shaft that are rotatably supported and positioned parallel to each other in a transmission. Both shafts are connected with one another via an eccentric device of the input shaft and a freewheel device disposed on the output shaft, as well as a connection device connecting the eccentric device and the freewheel device. The eccentric device includes several eccentric units that are disposed axially next to one another on the input shaft. The freewheel device includes several freewheel units that are disposed axially next to one another on the output shaft. To form each eccentric unit, the input shaft includes a guide section eccentrically offset with respect to its rotation axis, on whose jacket surface an eccentric component is rotatably supported. At least a connecting rod is rotatably disposed on the eccentric component during the design of the crank continuous variable transmission (crank CVT).
Through the rotation of an adjustment shaft disposed in a recess of the input shaft, the size of eccentricity of the eccentric component is changed with regard to the axis of rotation of the input shaft.
The units disposed on the output shaft have respective clamping bodies that are disposed between an inner ring formed by a section of the output shaft and an outer ring. The the surfaces of the outer ring and the inner ring are matched to each other such that the clamping bodies can block this rotation in a relative direction of rotation between the inner ring and outer ring, so that the outer ring and the inner ring are jointly rotated. In the other relative direction of rotation between the outer ring and the inner ring, no blocking effect is caused by the clamping bodies. The individual clamping bodies are actuated in the blocking direction, which can occur at least through a spring element. Individual clamp bodies are positioned next to each other in the circumferential direction, at least via a cage.
It is possible to make the clamping effect of the clamping bodies capable of switching with the help of switching units. Thereby, each switching unit is disposed between two neighboring clamping bodies. The switching units are synchronously actuatable and have, respectively, a rotatable disk-shaped section as well as a profiled section at which a torsion spring is disposed. The torsion spring is held between the profiled section and a neighboring clamping body. For this purpose, the torsion spring has a leg that can act against a clamping body in the corresponding blocking direction. The torsion spring and the profiled sections are eccentrically disposed with respect to the axis of rotation axis of the disk-shaped section, so that in a during rotation of the disk-shaped section a circumferential displacement of the spring element and the profiled sections takes place. The disk-shaped sections are disposed in a carrier part. In the case of rotation of the disk-shaped sections by approximately 180°, the bracing direction and/or the force direction of the torsion spring and/or the above-mentioned limb thereof changes with respect to the clamping bodies. It is apparent that such switching units are problematic with regard to its mechanical structure, its susceptibility to disturbance and/or service life, as well as its manufacture.
An object of the present invention, therefore, involves providing a switchable freewheel device for a transmission, one that is constructed comparatively simply out of relatively few parts.